Screw conveyor apparatus



April 28, 1959 A F. MULLER ET AL SCREW coNvEYoR APPARATUS Filed May 29,1956 United States Patent SCREW CONVEYOR APPARATUS Franz Mller, Refrath,Bezirk Koln, and Leonhard H.

Winners, Koln-Kalk, Germany, assignors to Klockner- Humboldt-Dentz A.G.,Koln (Rhine), Germany, a Ger man corporation Application May 29, 1956,Serial No. 588,180

8 Claims. (Cl. 214-17) The present invention relates to a conveyor fortinegrained pulverized material and to the maintaining of a gas-pressureseal for the supply means of the conveyor; and, more particularly, theinvention relates to a screw conveyor for conveying tine-grainedpulverized material from a plurality of hoppers or supply vessels, whilecontinuously maintaining a gas-pressure seal among the several supplyvessels each with respect to the other, and also with respect to theatmosphere.

The present application is a continuation in part of our copendingapplication, Serial No. 260,554, filed December 7, 1951, now abandoned.

lt is a principal-object of the present invention to provide a screwconveyor of this character wherein the gas pressure seal Will bemaintained notwithstanding the fact that one or more of the severalsupply vessels may have become empty.

The screw conveyor in accordance with the invention comprises ahorizontally elongated power-driven shaft which extends within a tubularpipe or duct coaxially therewith. At a plurality of points along theduct, longitudinally spaced supply apertures are formed therein in theupper side thereof. Each supply aperture communicates with a bin, hopperor similar supply vessel from which pulverized material is fed bygravity into the conveyor duct. Extending within the duct and past theseseveral supply apertures is a helical conveyor member mounted on theshaft and which feeds the pulverized material from the most upstream ofthe supply apertures and past one or more intermediate supply aperturesto the conveyor outlet. The conveyor helix is interrupted upstream ofeach of the supply apertures intermediate the most upstream aperture andthe conveyor outlet. This interruption of the conveyor helix leaves anintervening bare or smooth portion of the rotating shaft around whichthe pulverized material accumulates upstream of each intermediate supplyaperture thereby forming a gas-tight pressure seal of compact material.The interruption terminates at its downstream end in a circular disc ordam fixed to the shaft, each disc being located in communication withone of the intermediate supply apertures. The pulverized material isthus constrained to move upwardly into and out of each intermediatesupply aperture in order to surmount and flow over each revolving discor dam. If the supply of material at any intermediate aperture shouldbecome exhausted, material from any aperture located upstream of theaperture for which the supply is exhausted will move up into and downout of the exhausted supply duct thereby forming and maintaining asealing plug of pulverized material directly above the exhausted supplyaperture. This sealing plug of pulverized material maintains a gas sealnotwithstanding the fact that the duct in which it is formed wouldotherwise be empty. When a fresh suply of material becomes available atthe exhausted supply aperture, the weight of the new material will causeit to ow downwardly by gravity into the supply aperture as before, sothat the pulverized material Patented Apr. 28, 1959 is again fed to theconveyor along with material from any supply duct located upstreamthereof.

If the most upstream supply vessel should become exhausted, the pressureseal is maintained by a tubular plug of pulverized material surroundingthe bare portion of the shaft immediately upstream of the next supplyaperture.

Various additional objects, features and advantages of the inventionwill become apparent upon reading the following specification togetherwith the accompanying drawing forming a part hereof.

Referring to the drawing- Fig. l is a view in side elevationillustrating an embodiment of a screw conveyor in accordance with theinvention, the conveyor being shown in longitudinal section.

Fig. 2 is an enlarged fragmentary view showing the sealing plug which isformed at an exhausted supply aperture.

Referring to Fig. l, the conveyor comprises an elongated tubular duct10. A conveyor shaft 11 extends coaxially within the duct 10. At itsleft-hand end, the shaft 11 is connected to drive means, illustrativelyshown as an electric motor 13, by means of a coupling 14. Two supplyvessels such as hoppers 16 and 17 are illustrated, only their lowerconical ends being visible in the drawing.

At its lower end, the hopper 16 terminates in a collar ilange 19 whichis connected to a ilange 20 formed on the upper end of an inlet ductmember 22. Inlet duct member 22 is provided with a lower ilange member23. Lower flange 23 is connected to a cooperating flange 24, formed onan upstream inlet member Z5. The upstream inlet member 25 is mounted inthe Wall of the elongated tubular duct 10 and denes a most upstream portor inlet aperture 27.

The downstream hopper 17 is similarly connected through a flanged inletduct memlber 30 to` a downstream inlet member 31 which defines adownstream port or inlet aperture 32.

Mounted on the shaft 11 is a helical conveyor member or helix 34. Theconveyor helix 34 is fixed to shaft 11 for rotation therewith. Theconveyor helix 34 extends from a position beneath the upstream inletaperture 27 to a terminal point 35 located upstream of the downstreaminlet aperture 32.

A disc or collar 37 is mounted on shaft 11 for rotation therewith at acentral position directly beneath the downstream inlet aperture 32intermediate i-ts upstream and downstream edges so that the inletaperture 32 communicates with both sides of the disc 37. A smoothportion of shaft 11 extends from terminal point 35 to disc 37. A furtherhelical conveyor member or helix 38 extends downstream from the disc 37.If one or more additional downstream inlet apertures are provided, thenthe conveyor helix 38 will terminate upstream of the next aperture in amanner similar to the helix 34 which terminates at point 35. Similarly,a disc will be provided at each further downstream inlet aperture. If nofurther downstream inlet apertures are provided, then the helix 38 willextend continuously to the conveyor outlet (not shown).

In operation, the motor 13 drives the shaft 11 through coupling 14.Shaft 11 rotates in a counterclockwise direction as viewed from( theleft of Fig. 1. As a result, pulverized material 41 which is feddownwardly by gravity from hopper 16 will be conveyed to the rightwithin the duct 10 until it reaches the terminal point 35 at the righthand end of the conveyor helix 34. Downstream of terminal point 35, thematerial 41 from hopper 16 accumulates and compacts around the smoothportion of shaft 11 and forms a gas-tight pressure seal due to theabsence of the conveying helix 34 which terminates at point 35 and doesnot extend along this portion of the shaft 11 and because of theadditional impediment to lthe ow of material in that the pulverizedmaterial 41 must rise over and surmount the disc 37 in order to reachthe next conveyor member 38. VIn so doing, the material 41 isconstrained to move upwardly into the downstream inlet member 31 whereit merges with further pulverized material 42 flowing downwardly bygravity through the right-hand portion of the downstream inlet member31.

In the event that the supply of pulverized material 42 from thedownstream hopper 17 should become exhausted as shown in Fig. 2, thematerial 41 from the upstream hopper 16 will nevertheless continue to owover the disc 37. In owing over disc 37, it will move upwardly into thedownstream inlet member 31 and may extend upwardly into the flanged ductmember 3l?, forming a second sealing plug 43 to assist the gas pressureseals formed in the conveyor duct 10. When a new supply of pulverizedmaterial becomes available in the hopper 17, it will again movedownwardly by gravity through the downstream inlet member 31 and mergewith the material iowing over disc 37 in the same manner as it did priorto interruption of the downstream supply in hopper 17.

If the supply of pulverized material 41 in the upstream hopper 16 shouldbecome exhausted so that no material is available at the most upstreaminlet aperture 27, then the gas-tight seal is maintained by the tubularplug of pulverized material which surrounds the non-conveying section ofshaft 11 in the space between the downstream terminus of helix member 34at point 35 and the upstream side of disc 37.

While there have been shown and described what are believed to be thebest embodiments of the invention, it will be apparent to those skilledin the art that many modifications may be made therein within the spiritand scope of the invention as defined in the appended claims.

We claim:

l. Screw conveyor apparatus of the class described comprising a driveshaft having a direction at least the major component of which ishorizontal, a helical member mounted on said shaft for rotationtherewith and pitched to convey material downstream therealong, saidshaft extending beyond the downstream end of the helical member, acasing extending along said shaft coaxially therewith and confining theshaft and helical member, said casing having a least a first and asecond opening therein, supply means communicating with said casingthrough said first and second openings, and a disc in said casing andmounted on said shaft downstream of the helical member and adjacent saidsecond opening, whereby material must flow upwardly over said disc tomerge with material entering through said second opening of said casing.

2. Screw conveyor apparatus of the class described comprising arevolvably driven shaft having a substantial horizontal component ofdirection, a helix member mounted on said shaft for rotation therewithand pitched to convey material downstream therealong, said shaftextending beyond the downstream end of the helical member, a casingextending along said shaft coaxially therewith and confining the saidshaft and helix member, an upstream aperture in said casing, a materialsupply vessel communicating with said upstream aperture, a downstreamaperture in said casing, said downstream aperture also serving as amaterial inlet and being vertically disposed above a portion of theextension of said shaft beyond said helical member, and a disc in saidcasing and mounted on said shaft extension for rotation therewith on theportion beneath the said downstream aperture.

3. Screw conveyor apparatus of the class described comprising arevolvably driven shaft having a substantial horizontal component ofdirection, a first helix member mounted on said shaft for rotationtherewith and pitched to convey pulverized material downstreamtherealong,

a second helix member mounted on said shaft downstream of said firsthelix member, the upstream end of said second helix member being axiallyspaced from the downstream end of said first helix member, anupwardlydownwardly extending circular dam mounted on said shaft betweenthe proximal ends of the first and second helix members, a ductlextending along said shaft coaxially therewith and confining said firstand second helix members and said shaft, said duct having at least oneaperture for supplying material to the lirst helix substantiallyupstream of the downstream end of said first helix, said duct having aport communicating with both sides of the dam, and a material-supplyconduit communicating with said port, the material moved by said firsthelix member fiowing upwardly over said dam to merge with materialentering through said port.

4. Screw conveyor apparatus of the class described comprising arevoluble power-driven shaft having a substantial horizontal componentof direction, a first conveyor helix member mounted on said shaft forrotation therewith and pitched to convey pulverized material downstreamtherealong, a second conveyor helix member mounted on said shaftdownstream of said first helix member, the upstream end of said secondhelix member being axially spaced from the downstream end of said firsthelix member, an upwardly-downwardly extending circular dam mounted onsaid shaft at the upstream end of said helix member, a tubular ductextending along said shaft coaxially therewith and surrounding saidfirst and second helix members, said duct having a first supply apertureformed therein communicating with the upstream region of said firsthelix member, said duct further having a second supply aperture formedtherein communicating with both sides of said dam, a supply duct forpulverized material communicating individually with said first apertureand a further supply duct for pulverized material communicatingindividually with said second aperture.

5. Screw conveyor apparatus of the class described comprising ahorizontally elongated revoluble powerdriven shaft, a first conveyorhelix member mounted on said shaft for rotation therewith and pitched toconvey pulverized material downstream therealong, a second conveyorhelix member mounted on said shaft downstream of said first helixmember, the upstream end of said second helix member being axiallyspaced from the downstream end of said first helix member to leave anintermediate section of said shaft between said first and second helixmembers which is inactive for conveying purposes, a circular dam mountedon said shaft in advance and dening the downstream boundary of saidintermediate section of said second helix member, a tubular ductextending along said shaft coaxially therewith and surrounding saidfirst and second helix members including said space therebetween, afirst supply vessel for pulverized material disposed above said tubularduct, a first supply duct connecting said first supply vessel with theinterior of said tubular duct at the upstream region of said first helixmember, a second supply vessel for pulverized material disposed abovesaid tubular duct, and a second supply duct connected with said secondsupply vessel and communicating with the interior of said tubular ductat both sides of said dam.

6. Screw conveyor apparatus of the class described for conveyingpulverized material, said apparatus comprising a revoluble power-drivenshaft, a rst conveyor helix mounted on said shaft for rotationtherewith, a second conveyor helix mounted on said shaft downstream ofsaid first helix, both helices being pitched to convey pulverizedmaterial downstream along the shaft, the upstream end of said secondhelix being axially spaced from the downstream end of said first helixto leave an intermediate material sealing section of said shaftextending therebetween, a circular disc of diameter at least as great asthe diameter of said second helix disposed on said shaft assente at theupstream end of said second helix, a tubular duct extending along saidshaft coaxially therewith and closely surrounding said first and secondhelices for conning said pulverized material, said duct having a lirstsupply aperture formed therein communicating with the upstream region ofsaid rst helix, said duct further having a second supply aperture formedtherein communicating with both sides of said darn, and supply ducts forsaid pulverized material communicating individually with each of saidapertures.

7. Screw conveyor apparatus of the class described comprising asubstantially horizontal revoluble powerdriven shaft, a iirst conveyorhelix member mounted on said shaft for rotation therewith, a secondconveyor helix member mounted on said shaft downstream of said rst helixmember, both helices being pitched to convey pulverized materialdownstream along the shaft, the upstream end of said second helix memberbeing axially spaced from the downstream end of said first helix member,a circular dam concentrically fixed to said shaft for rotation therewithat the upstream end of said second helix member, a duct extending alongsaid shaft coaxially therewith and surrounding said rst and second helixmembers and said space therebetween, said duct having a rst supplyaperture formed therein communicating with the upstream region of saidrst helix member, said duct further having a second supply apertureformed therein communicating with both sides of said dam, a supply ductfor pulverized material communicating individually with said firstaperture and a further supply duct for pulverized material communicatingindividually with said second aperture, the material moved by the firsthelix member owing upwardly over said dam to merge with materialentering said second aperture.

8. Screw conveyor apparatus of the class described comprising ahorizontally elongated revoluble shaft, a

first conveyor helix member mounted on said shaft for rotation therewithand pitched to convey pulverized material downstream therealong, asecond conveyor helix member fixed to said shaft for rotation therewithdownstream of said first helix member, said second helix mem* ber beingpitched like said first helix member, the upstream end of said secondhelix member being axially spaced from the downstream end of said firsthelix member to leave a non-conveying section of said shafttherebetween, a circular dam of diameter at least as great as theexternal diameter of said second helix member concentrically mounted onsaid shaft abutting the upstream end of said second helix member, saidclam being xed to said shaft for rotation therewith, a tubular ductextending along said shaft coaxially therewith and surrounding said irstand second helix members, a rst supply vessel for pulverized materialdisposed above said tubular duct, a first supply duct connecting saidfirst supply vessel with the interior of said tubular duct at theupstream region of said first helix member, a second supply vessel forpulverized material disposed above said tubular duct, a second supplyduct connected with said second supply vessel and communicating with theinterior of said tubular duct at both sides of said dam, andpoweroperated means connected to said shaft for revolving said helixmembers and said dam.

References Cited in the flle of this patent UNITED STATES PATENTS2,021,991 Depew Nov. 26, 1935 2,176,092 Meduna Oct. 17, 1939 FOREIGNPATENTS 1,061,705 France Dec. 2, 1953 1,070,281 France Feb. 17, 1954

